1. Field of the Invention
The present invention relates to blade sharpening systems. More specifically, the invention relates to systems for sharpening spiral meat slicing blades.
2. Related Art
The spiral meat slicing blade disclosed in U.S. Pat. No. 4,050,370 (Schmidt et al.) has normally been sharpened on a sharpening device employing a stone sharpening abrasive. A significant disadvantage of this device is that, with continued sharpening, the radius of the sharpening abrasive is reduced. This reduced radius causes unreliable sharpening results due to the progressive change in contact area between the blade and the abrasive as the abrasive wears down. Further, the life of the blade is reduced when the contact area is changed through the reduced radius of the abrasive.
There is therefore a need to provide a system of sharpening blades in which the contact area between the blade and the abrasive is maintained substantially constant, even after large numbers of blades have been sharpened.
Another problem of known blade sharpening systems involves "blade chatter". Blade chatter is encountered when a blade being sharpened does not continually and smoothly contact the abrasive surface. Rather, the blade "jumps" periodically or aperiodically from the abrasive surface. Thereafter, a returning force must be applied (such as by a human applying pressure with his hand) to cause the blade to again contact the abrasive surface. This repetition of periods of contact, followed by periods of lesser contact or no contact, causes unevenness of blade sharpening.
Further, known methods of holding the blade against the abrasive surface have often caused either too little pressure or too much pressure between the blade and the abrasive surface. An improper amount of pressure causes blade sharpening to be unreliably sharpened, causing poorer cutting performance.
Therefore, there is a need to provide a blade sharpening system in which a proper amount of pressure is maintained between the blade and the abrasive surface, to reduce blade chatter.
Various blade sharpening systems are known in the art. For example, U.S. Pat. No. 4,635,402 (Sakabe et al.) discloses a knife sharpening apparatus for sharpening blades that are located on the periphery of a drum-shaped cutter used for shredding material (such as tobacco leaves) which are input to a shredding port. An abrasive wheel has a "plane" which rotates to grind a blade edge in a substantially longitudinal direction on the blade, so that it does not become serrated. The abrasive "plane" is not truly a plane, but is curved so as to conform to the cylindrical outer surface of the blade cylinder. This observation applies to other embodiments of the Sakabe et al. device.
U.S. Pat. No. 4,265,146 (Horrell) discloses a device for sharpening lawn mower blades which uses a disk-shaped abrasive wheel adapted for rotation by a standard hand drill. A clamp grasps the blade and allows it to reciprocate, in contact with the abrasive wheel. The Horrell patent discloses two angular orientations of the blade with respect to the abrasive wheel.
U.S. Pat. No. 3,883,995 (Ohashi) discloses a device for sharpening razor blades or scissors in which the razor blade is positioned above a cylindrical abrasive element and moved by a block.
U.S. Pat. No. 3,755,971 (Garcia) discloses a device for grinding sheers and scissors in which a grinding wheel is disposed at 5-25 degrees from the vertical (preferably 20 degrees). With the scissor blade secured to a platform, the platform assembly and scissor blade reciprocate in a direction so that the scissor blade contacts the grinding wheel at an oblique angle.
U.S. Pat. No. 895,749 (Gury) discloses a device for sharping both edges of a blade, the blade being attached to a longitudinally moveable rod so that the two edges of the blade may contact the periphery of cylindrical grinding wheel at a right angle.
The above systems do not enjoy the advantages possessed by the present invention in providing a constant contact surface between blade and abrasive, or in solving blade chatter problems. Some of these patents do not even relate to sharpening the type of blade on which the present invention is most advantageously used. Therefore, there is a need in the art to provide a blade sharpening system which overcomes the above limitations of known blade sharpening systems.